This research program is designed to provide information which is essential to understanding the molecular or cellular mechanism of action of hormones which regulate target renal cell function ultimately contributing to the regulation of extracellular volume, ion levels, etc. The contribution of specific plasma membrane components (subunits) to endocrine regulation with emphasis on the adenylate cyclase system, both plasma membrane and cytosol cyclic AMP-dependent protein kinase systems and specific membrane aldosterone receptors will be examined. Primary objectives of this research are: (1) to compare the renal cytosol and plasma membrane cyclic AMP-dependent protein kinase with regard to the molecular mechanism of cyclic AMP activation of the protein kinase in vitro as may be related to proposed regulator (receptor) and catalytic subunit mechanism, (2) to examine the mechanism of NaF activation of plasma membrane adenylate cyclase with emphasis on the interaction of F negative with membrane phospholipids as a potential mechanism, and (3) to examine the biochemical nature of the plasma membrane aldosterone receptor protein and study the physiological significance of this receptor as a potential regulatory influence on the cellular mechanism of action of polypeptide hormones in the kidney (steroid permissive effect), with emphasis on the effects of aldosterone on the cyclic AMP-dependent protein kinase system of adrenalectomized rat kidney plasma membranes. BIBLIOGRAPHIC REFERENCES: Forte, L.R., Nickols, G.A. andAnast, C.S., Renal Adenylate Cyclase and the Interrelationship Between Parathyroid Hormone and Vitamin D in the Regulation of Urinary Phosphate and Adenosine Cyclic 3', 5' Monophosphate Excretion, J. Clin. Invest. 57: 559-568 (1976). Anast, C.S., Winnacker, J.L., Forte, L.R. and Burns, T.W. Impaired Release of Parathyroid Hormone in Magnesium Deficiency, J. Clin. Endocrinol. Metab. 42:707-717 (1976).